Influence of Intraoperative Active and Passive Breaks in Simulated Minimally Invasive Procedures on Surgeons' Perceived Discomfort, Performance, and Workload

Laparoscopic surgeons are at high risk of experiencing musculoskeletal discomfort, which is considered the result of long-lasting static and awkward body postures. We primarily aimed to evaluate whether passive and active work breaks can reduce ratings of perceived discomfort among laparoscopic surgeons compared with no work breaks. We secondarily aimed to examine potential differences in performance and workload across work break conditions and requested the surgeons evaluate working with passive or active work breaks. Following a balanced, randomized cross-over design, laparoscopic surgeons performed three 90 min laparoscopic simulations without and with 2.5 min passive or active work breaks after 30 min work blocks on separate days. The simulation included the following tasks: a hot wire, peg transfer, pick-and-place, pick-and-tighten, pick-and-thread, and pull-and-stick tasks. Ratings of perceived discomfort (CR10 Borg Scale), performance per subtask, and perceived workload (NASA-TLX) were recorded, and the break interventions were evaluated (self-developed questionnaire). Statistical analyses were performed on the rating of perceived discomfort and a selection of the performance outcomes. Twenty-one participants (9F) were included, with a mean age of 36.6 years (SD 9.7) and an average experience in laparoscopies of 8.5 years (SD 5.6). Ratings of perceived musculoskeletal discomfort slightly increased over time from a mean level of 0.1 to 0.9 but did not statistically significantly differ between conditions (p = 0.439). Performance outcomes of the hot wire and peg transfer tasks did not statistically significantly differ between conditions. The overall evaluation by the participants was slightly in favor regarding the duration and content of active breaks and showed a 65% likelihood of implementing them on their own initiative in ≥90 min-lasting laparoscopic surgeries, compared with passive breaks. Both passive and active breaks did not statistically significantly influence ratings of perceived discomfort or perceived workload in a 90 min simulation of laparoscopic surgery, with an overall low mean level of perceived discomfort of 0.9 (SD 1.4). As work breaks do not lead to performance losses, rest breaks should be tested in real-life situations across a complete working shift, where perceived discomfort may differ from this laboratory situation. However, in this respect, it is crucial to investigate the acceptance and practicality of intraoperative work breaks in feasibility studies in advance of assessing their effectiveness in follow-up longitudinal trials.

Wrist Extensor Muscle Fatigue During a Dual Task With Two Muscular and Cognitive Load Levels in Younger and Older Adults

OBJECTIVE

To examine the effect of concurrent physical and cognitive demands as well as age on indicators of muscle fatigue at the wrist.

BACKGROUND

There are few studies examining risk indicators for musculoskeletal disorders associated with work-related physical and cognitive demands that often occur simultaneously in the workplace.

METHODS

Twenty-four gender-balanced older and 24 gender-balanced younger (mean age 60 and 23 years) participants performed four 30 min dual tasks. Tasks differed by the muscular load level during force tracking: 5% and 10% of maximum voluntary contraction force (MVC) and concurrent cognitive demands on the working memory: easy and difficult. Muscle fatigue was assessed by MVC decline and changes in surface electromyography (increased root mean square: RMS, decreased median frequency: MF) at the extensor digitorum (ED) and extensor carpi ulnaris (EU).

RESULTS

A decline in MVC was found in all participants when tracking was performed at 10% MVC (mean ± SD: 137.9 ± 49.2 - 123.0 ± 45.3 N). Irrespective of age, muscular, or cognitive load, RMS increased (ED 12.3 ± 6.5 - 14.1 ± 7.0% MVE, EU 15.4 ± 7.6 - 16.9 ± 8.6% MVE) and MF decreased (ED 85.4 ± 13.6 - 83.2 ± 12.8 Hz, EU 107.2 ± 17.1 - 104.3 ± 16.7 Hz) in both muscles. However, changes in MF of EU tended to be more pronounced in the older group at higher cognitive and lower muscular load, without reaching statistical significance.

CONCLUSION

Maximum voluntary contraction indicated no interaction between muscle fatigue, cognitive load, or age. However, the tendencies toward altered muscle activity due to an increase in cognitive load and older age suggest muscular adaptations while maintaining tracking performance during the onset of fatigue signs in the sEMG signal.

APPLICATION

If the tendencies in muscle activity are confirmed by further studies, ergonomic assessments in industrial workplaces should consider cognitive load and age when describing the risk of musculoskeletal disorders.

Musculoskeletal demands in microsurgery-an explorative study comparing the ergonomics of microscope and 3D exoscope

To assess neurosurgeons' physical demands and investigate ergonomic aspects when using microsurgical visualization devices. Six neurosurgeons performed micro-surgical procedures on cadaveric specimens using the prototype of a digital 3D exoscope system (Aeos®, Aesculap, Tuttlingen, Germany) and a standard operating microscope (Pentero 900, Zeiss, Oberkochen, Germany) at two different patient positions (semisitting (SS), supine (SP)). The activities of the bilateral upper trapezius (UTM), anterior deltoid (ADM), and lumbar erector spinae (LEM) muscles were recorded using bipolar surface electromyography and neck flexion, arm abduction, and arm anteversion angles by gravimetrical posture sensors. Perceived discomfort frequency was assessed and subjects compared the two systems in terms of usability, posture, physical and mental demands, and working precision. Using the exoscope led to reduced ADM activity and increased UTM and LEM activity during SS position. The neck was extended when using the exoscope system with lower arm anteversion and abduction angles during the SS position. Subjects reported discomfort at the shoulder-neck area less frequently and lower physical demands when using the Aeos®. However, mental demands were slightly higher and two subjects reported lower working precision. The exoscope system has the potential to reduce the activity of the ADM by changing surgeons arm posture which may be accompanied by less discomfort in the shoulder-neck area. However, dependent on the applied patient position higher muscle activities could occur in the UTM and LEM.

Influence of Face Masks on Physiological and Subjective Response during 130 Min of Simulated Light and Medium Physical Manual Work-An Explorative Study

BACKGROUND

Undesirable side effects from wearing face masks during the ongoing COVID-19 pandemic continue to be discussed and pose a challenge to occupational health and safety when recommending safe application. Only few studies examined the effects of continuously wearing a face mask for more than one hour. Therefore, the influence of wearing a medical mask (MedMask) and a filtering facepiece class II respirator (FFP2) on the physiological and subjective outcomes in the course of 130 min of manual work was exploratively investigated. Physical work load and cardiorespiratory fitness levels were additionally considered as moderating factors.

METHODS

Twenty-four healthy subjects (12 females) from three different cardiorespiratory fitness levels each performed 130 min of simulated manual work with light and medium physical workload using either no mask, a MedMask or FFP2. Heart rate, transcutaneous oxygen and carbon dioxide partial pressure (P_tcO₂, P_tcCO₂) as well as perceived physical exertion and respiratory effort were assessed continuously at discrete time intervals. Wearing comfort of the masks were additionally rated after the working period.

RESULTS

There was no difference in time-dependent changes of physiological outcomes when using either a MedMask or a FFP2 compared to not wearing a mask. A stronger increase over time in perceived respiratory effort occurred when the face masks were worn, being more prominent for FFP2. Physical workload level and cardiorespiratory fitness level were no moderating factors and higher wearing comfort was rated for the MedMask.

CONCLUSION

Our results suggest that using face masks during light and medium physical manual work does not induce detrimental side effects. Prolonged wearing episodes appeared to increase respiratory effort, but without affecting human physiology in a clinically relevant way.

Intraoperative active and passive breaks during minimally invasive surgery influence upper extremity physical strain and physical stress response-A controlled, randomized cross-over, laboratory trial

OBJECTIVE

Investigate the effect of passive, active or no intra-operative work breaks on static, median and peak muscular activity, muscular fatigue, upper body postures, heart rate, and heart rate variability.

BACKGROUND

Although laparoscopic surgery is preferred over open surgery for the benefit of the patient, it puts the surgeons at higher risk for developing musculoskeletal disorders especially due to the less dynamic and awkward working posture. The organizational intervention intraoperative work break is a workplace strategy that has previously demonstrated positive effects in small-scale intervention studies.

METHODS

Twenty-one surgeons were exposed to three 90-min conditions: no breaks, 2.5-min passive (standing rest) or active (targeted stretching and mobilization exercises) breaks after 30-min work blocks. Muscular activity and fatigue of back, shoulder and forearm muscles were assessed by surface electromyography; upper body posture, i.e., spinal curvature, by inclination sensors; and heart rate and variability (HRV) by electrocardiography. Generalized estimating equations were used for statistical analyses. This study (NCT03715816) was conducted from March 2019 to October 2020.

RESULTS

The HRV-metric SDNN tended to be higher, but not statistically significantly, in the intervention conditions compared to the control condition. No statistically significant effects of both interventions were detected for muscular activity, joint angles or heart rate.

CONCLUSION

Intraoperative work breaks, whether passive or active, may counteract shoulder muscular fatigue and increase heart rate variability. This tendency may play a role in a reduced risk for developing work-related musculoskeletal disorders and acute physical stress responses.

Using a Back Exoskeleton During Industrial and Functional Tasks-Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial

OBJECTIVE

To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton.

BACKGROUND

Back-support exoskeletons have the potential to reduce work-related physical demands.

METHODS

Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS.

RESULTS

During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm.

CONCLUSION

Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable.

APPLICATION

These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

Limitations in evaluating COVID-19 protective face masks using open circuit spirometry systems: respiratory measurement mask introduces bias in breathing pressure and perceived respiratory effort

Objective.In response to the COVID-19 pandemic and the resulting widespread use of protective face masks, studies have been and are being conducted to investigate potential side effects of wearing masks on the performance and physiological parameters of wearers. The purpose of the present study is to determine whether and to what extent the use of a respiratory measurement (RM) mask-which is normally used during open-circuit spirometry-influences the results of these types of studies.Approach.34 subjects were involved in this intra-subject study with a cross-over design. Four different protective face masks, Community Mask, medical Mouth-Nose-Protection Mask, Filtering Face Piece Mask Class 2 (FFP2), and FFP2 with exhalation valve (FFP2ex), were tested at rest and during deep breathing by using or not using a RM mask (RM versus noRM). Breathing pressure inside the protective face masks was measured during inhalation and exhalation, and subjects rated breathing effort using an 11-stage Borg scale.Main results.The use of an additional RM mask-worn over the protective face masks-significantly increased inspiratory pressures under all mask conditions. The respiratory pressure rises to a level that substantially distorts the results. Expiratory pressure was also significantly increased except for the FFP2ex mask condition. The perceived respiratory effort was significantly increased by 1.0 to 2.8 steps on the Borgs scale for all mask conditions compared with noRM.Significance.We strongly recommend avoiding the use of RM masks for evaluating the effects of protective face masks on human physiology and subjective perception.

Comparison of a Group-/Home-Based and a Weight-Machine-Based Exercise Training for Patients with Hip or Knee Osteoarthritis-A Secondary Analysis of Two Trial Interventions in a Real-World Context

This study aimed to compare an individual weight-machine-based strengthening program (MbT) with a group-/homebased training offering strengthening/functional exercises (GHT) in a general health care setting. A total of 657 participants (GHT = 521, MbT = 136) suffering from hip/knee OA were included and analysed with a pre-post design (baseline (T0)/3-months (T1)). Primary outcomes were pain and physical functioning (Western Ontario and McMaster Universities Osteoarthritis Index, range 0-10). Additionally, adherence and perceived patient benefit were measured (T1). Data were analysed with linear mixed models (time, treatment, baseline pain/physical impairment severity) adjusted for patient characteristics. No significant between-group differences in pain reduction/functional improvements (time*treatment*baseline pain/physical impairment severity, pain/function: n.s.; time*treatment, pain: p = 0.884, function: p = 0.067). Within-group improvements were dependent on baseline severity: Higher severity levels demonstrated larger changes from baseline. Perceived patient-benefit (very high to high, GHT: 78%, MbT: 92%) and exercise adherence (Dropouts T1: GHT: 27.8%, MbT: 16.2%; adherence to supervised sessions: GHT: 89%, MbT: 92%) was slightly better in the MbT. In summary, both MbT and GHT, showed positive results for patients with at least moderate disease symptoms. Findings for physical functioning, perceived patient-benefit, exercise adherence hint towards a superiority of MbT. Individual preferences should be considered when prescribing exercise therapy. Trial registration: (1) German Clinical Trial Register DRKS00009251. Registered 10 September 2015. (2) German Clinical Trial Register DRKS00009257. Registered 11 September 2015.

Effects of a Passive Back-Support Exoskeleton on Knee Joint Loading during Simulated Static Sorting and Dynamic Lifting Tasks

Due to the load shifting mechanism of many back-support exoskeletons (BSEs), this study evaluated possible side effects of using a BSE on knee joint loading. Twenty-nine subjects (25.9 (±4.4) years, 179.0 (±6.5) cm; 73.6 (±9.4) kg) performed simulated static sorting and dynamic lifting tasks, including stoop and squat styles and different trunk rotation postures. Ground reaction force, body posture and the force between the chest and the BSE's contact interface were recorded using a force plate, two-dimensional gravimetric position sensors, and a built-in force sensor of the BSE, respectively. Using these parameters and the subject's anthropometry, median and 90th percentile horizontal (HOR₅₀, HOR₉₀) and vertical (VERT₅₀, VERT₉₀) tibiofemoral forces were calculated via a self-developed inverse quasi-static biomechanical model. BSE use had a variable effect on HOR₅₀ dependent on the working task and body posture. Generally, VERT₅₀ increased without significant interaction effects with posture or task. HOR₉₀ and VERT₉₀ were not affected by using the BSE. In conclusion, utilizing the investigated exoskeleton is likely to induce side effects in terms of changed knee joint loading. This may depend on the applied working task and the user's body posture. The role of these changes in the context of a negative contribution to work-related cumulative knee exposures should be addressed by future research.

Postural Control When Using an Industrial Lower Limb Exoskeleton: Impact of Reaching for a Working Tool and External Perturbation

OBJECTIVE

To investigate postural control related to a lower limb exoskeleton (Chairless Chair) when (a) reaching for a working tool, and (b) an external perturbation occurs.

BACKGROUND

Lower limb exoskeletons aiming to reduce physical load associated with prolonged standing may impair workers' postural control and increase the risk of falling.

METHOD

Forty-five males were reaching for an object (3-kg dumbbell) at the lateral end of their reaching area without the exoskeleton in upright standing (STAND) and with the exoskeleton at a high (EXO_HIGH.SEAT) and low sitting position (EXO_LOW.SEAT). The task was performed with the object placed in three different angles (120°, 150°, and 180°) in the transversal plane. The minimum absolute static postural stability (SS_ABS.MIN) as the shortest distance (mm) of the center of pressure to the base of support border was measured (zero indicates risk of falling). Additionally, eight subjects were standing without the exoskeleton or sitting on it (EXO_HIGH.SEAT and EXO_LOW.SEAT) while being pulled backward. The tilting moment when subjects lost their balance was assessed.

RESULTS

SS_ABS.MIN was lower when using the exoskeleton (p < .05) but still about 17 mm. The location of the object to be reached had no influence. Tilting moments of less than 30 nm were sufficient to let people fall backward when sitting on the exoskeleton (50 nm for STAND).

CONCLUSION

Impairments in postural control by the exoskeleton may not be relevant when reaching laterally for objects up to 3 kg. When an external perturbation occurs, the risk of falling may be much higher; irrespective of factors like uneven or slippery flooring.

APPLICATION

The risk of falling using the exoskeleton seems to be low when reaching laterally for an object of up to 3 kg. In situations where, for example, a collision with coworkers is likely, this exoskeleton is not recommended.

A passive back exoskeleton supporting symmetric and asymmetric lifting in stoop and squat posture reduces trunk and hip extensor muscle activity and adjusts body posture - A laboratory study

The influence of a passive exoskeleton was assessed during repetitive lifting with different lifting styles (squat, stoop) and orientations (frontal/symmetric, lateral/asymmetric) on trunk and hip extensor muscle activity (primary outcomes), abdominal, leg, and shoulder muscle activity, joint kinematics, and heart rate (secondary outcomes). Using the exoskeleton significantly and partially clinically relevant reduced median/peak activity of the erector spinae (≤6%), biceps femoris (≤28%), rectus abdominis (≤6%) and increased median/peak activity of the vastus lateralis (≤69%), trapezius descendens (≤19%), and median knee (≤6%) and hip flexion angles (≤11%). Using the exoskeleton had only limited influence on muscular responses. The findings imply the exoskeleton particularly supports hip extension and requires an adjusted body posture during lifting with different styles and orientations. The potential of using exoskeletons for primary/secondary prevention of musculoskeletal disorders should be investigated in future research including a greater diversity of users in terms of age, gender, health status.

The Influence of Neuroticism on the Muscle Response in the Trapezius and Frontalis Muscles to Anticipatory Stress

Abstract. Objective quantification of mental stress in the workplace would be beneficial for designing work tasks to avoid the negative consequences of mental stress. Methods such as surface electromyography have proven to be sensitive to mental demands. However, there is little knowledge about the muscle response and moderating factors during anticipatory stress paradigms. This study examined whether the personality dimension neuroticism moderates the muscle response to the expectation of an unpredictable electrical shock. Forty-seven subjects underwent three expectation phases, in which they could expect a pleasant audio signal (NoShock) or an electric shock in two conditions (anticipation of the first: Shock1, and second electric shock: Shock2) at an unpredictable moment. The frontalis muscle activity and the upper and upper/middle parts of the trapezius muscle were recorded using surface electromyography. Neuroticism was surveyed using the Big Five Inventory to assign the subjects to a group with lower or higher neuroticism. Shock1 only induced higher trapezius muscle activity in the higher neuroticism group, which vanished during Shock2, while the frontalis muscle showed no significant effects. The results suggest that neuroticism should be considered a moderating factor in assessing anticipatory stress using surface electromyography at the trapezius muscle.

Secondary Analysis of a Study on Exercise Therapy in Hip Osteoarthritis: Follow-Up Data on Pain and Physical Functioning

We evaluated the short- and longer-term effects of exercise therapy in hip osteoarthritis patients (OA) at baseline, three, six, and 12 months in a randomized setting, followed by a non-randomized setting. The primary randomized intervention (E = exercise, P = placebo–ultrasound, C = control) was followed by a voluntary three-month exercise therapy for P and C (renamed P-E, C-E). Participants randomized to E were not offered treatment again (E-C). Effect sizes (ES; 95% CI) were calculated for within-group effects across time for bodily pain (SF-36) and WOMAC pain, function, and stiffness. ANCOVAs of post-treatment scores were used for group comparison after the group-specific exercise intervention phase. Exercise adherence was assessed and related to post-treatment scores of clinical outcomes. Data of 115 participants of the RCT eligible for follow-up and completing exercise therapy were included into our analyses. Small to medium beneficial long-term effects of cumulative interventional effects, including exercise training, persisted in all groups. Group E-C (n = 49) showed significant 12 months vs. baseline within-group ES in all outcomes (ES 0.39–0.59) except stiffness. Findings were less prominent for exercise therapy in a non-randomized setting (C-E, P-E, both n = 33). Differences are partially explained by adherence rates, highlighting the relevance of therapy compliance strategies. Short-term between-group differences (ANCOVAs) only showed statistically significant differences for WOMAC function between P-E and E-C in favor of E-C (6.4 (95% CI 1.6–11.2; score range 0–100)).

The influence of using exoskeletons during occupational tasks on acute physical stress and strain compared to no exoskeleton - A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis determined the effects of using an exoskeleton during occupational tasks on physical stress and strain compared to not using an exoskeleton.

METHODS

Systematic electronic database searches were performed and the review was prepared according to the PRISMA guidelines. Treatment effects on the predefined outcomes were calculated using standardized mean differences for continuous outcomes in several meta-analyses using Review Manager 5.3. Registration: PROSPERO (CRD42020168701).

RESULTS

63 articles were included in qualitative syntheses and 52 in quantitative, but most of them did not extensively evaluate musculoskeletal stress and strain and the risk of bias was rated high for all included studies. Statistically significant effects of using back, upper-limb, or lower-limb exoskeletons have been observed in the supported body areas (e.g. reduced muscle activity, joint moments and perceived strain). Studies which did not exclusively focus on the supported body area also showed statistically significant effects in the non-supported areas (e.g. changed muscle activity and perceived strain) and in physiological outcomes (e.g. reduced energy expenditure).

CONCLUSIONS

Using an exoskeleton during occupational tasks seems to reduce user's acute physical stress and strain in the exoskeleton's target area. However, impact on workers' health is still unknown, primarily because of missing long-term evaluations under real working conditions. Furthermore, this systematic review highlights a lack of studies (1) following high quality methodological criteria, (2) evaluating various inter-related stress and strain parameters instead of only focusing on one specific, and (3) evaluating non-target body areas instead of only the directly supported body area.

Assessment of work-related hand and elbow workloads using measurement-based TLV for HAL

Direct-measurement-based methods for assessing workloads of the hand or elbow in the field are rare. Aim of the study was to develop such a method based on the Threshold Limit Value for Hand Activity Level (TLV for HAL). Hence, HAL was quantified using kinematic data (mean power frequencies, angular velocities and micro-pauses) and combined with electromyographic data (root-mean-square values) in order to generate a measurement-based TLV for HAL (mTLV for HAL). The multi-sensor system CUELA including inertial sensors, potentiometers and a 4-channel surface electromyography module was used. For wrist and elbow regions, associations between mTLV for HAL and disorders/complaints (quantified by odds ratios (OR [95%-confidence interval])) were tested exploratively within a cross-sectional field study with 500 participants. Higher workloads were frequently significantly associated with arthrosis of distal joints (9.23 [3.29-25.87]), wrist complaints (2.89 [1.63-5.11]) or elbow complaints (1.99 [1.08-3.67]). The new method could extend previous application possibilities.

Development of a musculoskeletal model of the wrist to predict frictional work dissipated due to tendon gliding resistance in the carpal tunnel

Carpal tunnel syndrome is an entrapment neuropathy that has been associated with the aggravation of tendon gliding resistance due to forceful, high velocity, awkwardly angled, and repetitive wrist motions. Cadaveric and epidemiological studies have shown that combinations of these risk factors have a more than additive effect. The aim of the current study was to develop a musculoskeletal model of the wrist that could evaluate these risk factors by simulating frictional work dissipated due to the gliding resistance of the third flexor digitorum superficialis tendon. Three flexion angle zones, three extension angle zones, five levels of task repetitiveness, and five levels of task effort were derived from ergonomic standards. Of the simulations performed by systematically combining these parameters, the extreme wrist flexion zone, at peak task repetitiveness and effort, dissipated the most frictional work. This zone dissipated approximately double the amount of frictional work compared to its equivalent zone in extension. For all motions, a multiplicative effect of the combination of task repetitiveness and effort on frictional work was identified by the musculoskeletal model, corroborating previous epidemiological and experimental studies. Overall, these results suggest that the ergonomic standards for wrist flexion-extension may need to be adjusted to reflect equivalent biomechanical impact and that workplace tasks should be designed to minimise exposure to combinations of highly repetitive and highly forceful work, especially when the wrist is highly flexed.

The use of exoskeletons in the occupational context for primary, secondary, and tertiary prevention of work-related musculoskeletal complaints

OCCUPATIONAL APPLICATIONS This guideline includes 20 recommendations and four key statements that achieved consensus or strong consensus regarding the application of exoskeletons in the workplace for the prevention of musculoskeletal complaints and diseases, the general use and implementation of exoskeletons, and recommendations for risk assessment. The guideline is intended for company physicians, occupational physicians, ergonomists, occupational safety specialists, and employers, and serves as information for all other actors in practical occupational safety. Due to the lack of evidence from the scientific literature, the recommendations and key statements are the result of expert discussions that were conducted at a consensus conference in accordance with the Regulations of the Association of the Scientific Medical Societies in Germany, moderated by an external consultant.

Active and passive work breaks during simulated laparoscopy among laparoscopic surgeons: study protocol for a controlled, randomised cross-over laboratory trial

INTRODUCTION

Laparoscopy has partially replaced open surgery due to the lower infection rate for the patient and hence better and shorter recovery. However, the surgeon's physical load is higher due to longer duration static and awkward body postures, increasing the risk for developing work-related musculoskeletal disorders. Interventions of an organisational nature are work breaks, being either passive or active. The primary objectives of this study are to determine whether passive and active work breaks lead to less discomfort than no work breaks and whether active work breaks lead to less discomfort than passive work breaks.

METHODS AND ANALYSIS

A controlled, randomised cross-over trial will be performed in the laboratory, of which its protocol is described here according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013 Statement. Recruitment of 21 laparoscopic surgeons started in April 2019 and the study is ongoing. The participating surgeons will perform three 1.5 hour experimental conditions, one without work breaks, one with 2.5 min passive work breaks including rest, and one with 2.5 min active work breaks including mobility and stretching exercises. The work breaks will be taken after 30 and 60 min of work. During the experiments, outcomes will be recorded. The primary outcome is rating of perceived discomfort measured on an 11-point numeric rating scale. The secondary outcomes are performance, muscle activity of selected muscles, upper body angles, heart rate, workload and subjective evaluation of both interventions. The collected data will be tested using a one-way or two-factorial repeated-measures analysis of variance.

ETHICS AND DISSEMINATION

Ethical approval of the study protocol was received by the local medical ethical committee of the University of Tübingen in February 2019 (no 618/2018BO2). The results of this study will be presented at national and international conferences, submitted for publications in peer-reviewed journals and serve as the starting point for a feasibility study.

TRIAL REGISTRATION NUMBER

NCT03715816.

Adjusting working conditions and evaluating the risk of infection during the COVID-19 pandemic in different workplace settings in Germany: a study protocol for an explorative modular mixed methods approach

INTRODUCTION

Currently, many countries, affected by the COVID-19 pandemic, discuss how the 'lockdown-restrictions' could be lifted to restart the economy and public life after the first wave of the COVID-19 disease has subsided. This study protocol describes an approach designed to provide an in-depth understanding of how companies and their employees in Germany deal with their working conditions during the COVID-19 pandemic. We are also interested in how and why the risk of infection with SARS-CoV-2 could vary across different professional activities, company sites and regions with different epidemiological activity or infection control measures in Germany. We expect the results of this study to contribute to the development of working conditions protecting the health of employees during and beyond the COVID-19 pandemic.

METHODS AND ANALYSIS

An explorative multimodal mixed methods approach will be applied. Module 1 comprises a document analysis of prevailing federal and regional laws and regulations at the respective location of the participating company. Module 2 includes qualitative interviews with key actors at different companies. Module 3 is a repeated standardised employee survey designed to capture potential changes in the participants' experiences and attitudes towards working conditions, occupational safety regulations/measures, and infection control measures during the COVID-19 pandemic. Module 4 comprises SARS-CoV-2 seroprevalence testing. This is carried out by the medical service of the participating company sites as a voluntary offer for employees. Qualitative data will be analysed through document and content analysis. The complexity of the quantitative analysis depends on the response rates of modules 3 and 4.

ETHICS AND DISSEMINATION

The approval of the study design was received in June 2020 from the responsible local ethical committee of the Medical Faculty, University of Tübingen and University Hospital Tübingen (No. 423/2020BO). The results will be presented at national and international conferences and published in peer-reviewed journals.

Physiological changes during prolonged standing and walking considering age, gender and standing work experience

Occupational standing is associated with musculoskeletal and venous disorders. The aim was to investigate whether lower leg oedema and muscle fatigue development differ between standing and walking and whether age, gender and standing work habituation are factors to consider. Sixty participants (15 young females, 15 young males, 15 older males, and 15 young males habituated to standing work) were included and required to stand/walk for 4.5 hours in three periods with two seated breaks. Waterplethysmography/bioelectrical impedance, muscle twitch force and surface electromyography were used to assess lower leg swelling (LLS) and muscle fatigue as well as gastrocnemius muscle activity, respectively. While standing led to LLS and muscle fatigue, walking did not. Low-level medial gastrocnemius activity was not continuous during standing. No significant influence of age, gender and standing habituation was observed. Walking can be an effective prevention measure to counteract the detrimental effects of quasi-static standing.Practitioner summary: Prolonged standing leads to lower leg oedema and muscle fatigue while walking does not. The primary cause of fatigue may be in other muscles than the medial gastrocnemius. Walking may be an effective prevention measure for health risks of occupational standing when included intermittently.Abbreviation: BI: bioelectrical impedance; LLS: lower leg swelling; SEMG: surface electromyography; MTF: muscle twitch force; WP: waterplethysmography; Bsl: Baseline; L: Lunch; E: Evening; MTM: method times measurement; EA: electrical activity; IQR: interquartile range; p: percentile; M: mean; SE: standard error; Adj: adjusted.

A 12-week exercise program for patients with hip osteoarthritis has no influence on gait parameters: A secondary analysis of a randomized controlled trial

BACKGROUND

Hip osteoarthritis is a major musculoskeletal disorder in the elderly. Evidence is given for the efficacy of exercise interventions in terms of self-reported physical functioning and pain. However, it has not yet been fully examined whether exercises influence gait.

RESEARCH QUESTION

The purpose of this RCT therefore was to evaluate effects of a 12-week exercise program on kinematic gait variables in subjects with hip osteoarthritis.

METHODS

210 participants were randomly assigned to exercise, non-treated control, or placebo ultrasound groups. The 12-week exercise intervention combined a weekly group session with home-based exercises (2/week), which entailed exercises for motor learning, flexibility, strengthening, and balance. Placebo ultrasound was given once a week. A 6-camera motion capture system was used for data collection. Data were derived from shod walking at self-selected speeds. Spatio-temporal and hip and knee joint angles of the stance phase were calculated. Data were averaged across five trials. Measurements were taken prior to and immediately after the intervention period. ANOVA/Kruskall-Wallis-Tests were used to analyze between-group effects for differences between test days. Pairwise comparisons were subsequently conducted in case of significant model effects. Data were analyzed per protocol (n = 185).

RESULTS

No statistically significant differences were detected for any of the outcome measures.

SIGNIFICANCE

Although hip muscle strength and gait quality are related, strength training of the hip-surrounding musculature without specific gait training elements cannot improve spatio-temporal gait characteristics or hip and knee joint angles in subjects with mild to moderate hip osteoarthritis. If gait should explicitly be improved through exercise, interventions must incorporate a relevant portion of gait-related tasks.

Sex differences in muscle activity and motor variability in response to a non-fatiguing repetitive screwing task

Background

Musculoskeletal disorders are more prevalent among women than among men, which may be explained by aspects of motor control, including neuromuscular requirements and motor variability. Using an exploratory approach, this study aimed to evaluate sex differences in neuromuscular responses and motor variability during a repetitive task performed on 3 days.

Methods

Thirty women and 27 men performed the non-fatiguing, repetitive, 1-h screwing task. For neuromuscular responses, the mean and difference values of static, median, and peak percentile muscle activity levels (normalized to a reference voluntary contraction force) and, for motor variability, the mean and difference values of relative and absolute cycle-to-cycle variability across days were compared between both sexes for each muscle. A mixed-design analysis of variance was used to assess differences between both sexes.

Results

The non-fatiguing character of the screwing task was confirmed by the absence of decreased force levels in maximal voluntary contractions performed before and after the task and by absence of electromyographic signs of muscle fatigue. The static and median muscle activity levels tended to be higher among women (on average 7.86 and 27.23 %RVE) than men (on average 6.04 and 26.66 %RVE). Relative motor variability of the flexor and biceps muscles and absolute motor variability of both upper arm muscles were lower in women (on average 0.79 and 29.70 %RVE) than in men (on average 0.89 and 37.55 %RVE). The median activity level of both upper arms muscles tended to decrease within days among women (on average - 2.63 %RVE) but increase among men (on average + 1.19 %RVE). Absolute motor variability decreased within days among women (on average - 5.32 to - 0.34%RVE), whereas it tended to decrease less or increase within days among men (on average - 1.21 to + 0.25 %RVE).

Conclusion

Women showed higher levels of muscle activity and lower initial relative and absolute motor variability than males when performing the same occupational task, implying women may have a higher risk for developing disorders and point to both sexes using different intrinsic motor control strategies in task performance. Clearly, biological aspects alone cannot explain why women would be at higher risk for developing disorders than men. Therefore, a wider range of individual and environmental factors should be taken into account for optimizing work station designs and organizations by taking into account sex differences.

Influence of a passive lower-limb exoskeleton during simulated industrial work tasks on physical load, upper body posture, postural control and discomfort

This study investigated the effect of wearing a passive lower-limb exoskeleton on physical load, kinematics, postural control, and discomfort. 45 healthy males participated and were exposed to three 21-min simulations, including screwing, cable-mounting, and clip-fitting. Each exposure comprised one of three exoskeleton statuses (standing, high and low sitting on exoskeleton) and three working distances (optimal, far, very far). The order of exoskeleton status and working distance were randomized across subjects. A force platform was used to calculate the mean center of pressure (COP) and absolute (SS_ABS) and relative static postural stability (SS_REL) as measures of postural control as well as the weight transferred to the exoskeleton supports as indicator of physical load. Neck and back angles were recorded together with electrical activity of four bilateral muscles (trapezius, erector, vastus, gastrocnemius). Discomfort was recorded before and after each exposure on an 11-point numeric rating scale. Physical load decreased due to the exoskeleton carrying up to 64% of the subject's body mass. The COP remained within the base of support with the lowest values of static postural stability for high sitting (27%). During sitting, vastus activity increased (∼95-135%) while gastrocnemius activity decreased (∼25%) compared to standing. Trapezius and erector activity levels showed only minor differences between exposures. Larger working distances resulted in a more anterior COP and increased erector activity. Standing without exoskeleton was related to less discomfort (0.5) than sitting on the exoskeleton (∼1.3). Working postures and distances changed SS_REL and activity levels of the vastus, gastrocnemius, and erector, but not SS_ABS. However, postural stability did not approach a critical state in our simulations without external perturbations. Therefore, investigating exoskeletons in the field will provide useful information about their effectiveness and usability in dynamic working situations where external forces could occur.

Work-break schedules for preventing musculoskeletal symptoms and disorders in healthy workers

BACKGROUND

Work-related musculoskeletal disorders are a group of musculoskeletal disorders that comprise one of the most common disorders related to occupational sick leave worldwide. Musculoskeletal disorders accounted for 21% to 28% of work absenteeism days in 2017/2018 in the Netherlands, Germany and the UK. There are several interventions that may be effective in tackling the high prevalence of work-related musculoskeletal disorders among workers, such as physical, cognitive and organisational interventions. In this review, we will focus on work breaks as a measure of primary prevention, which are a type of organisational intervention.

OBJECTIVES

To compare the effectiveness of different work-break schedules for preventing work-related musculoskeletal symptoms and disorders in healthy workers, when compared to conventional or alternate work-break schedules.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PsycINFO, SCOPUS, Web of Science, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform, to April/May 2019. In addition, we searched references of the included studies and of relevant literature reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of work-break interventions for preventing work-related musculoskeletal symptoms and disorders among workers. The studies were eligible for inclusion when intervening on work-break frequency, duration and/or type, compared to conventional or an alternate work-break intervention. We included only those studies in which the investigated population included healthy, adult workers, who were free of musculoskeletal complaints during study enrolment, without restrictions to sex or occupation. The primary outcomes were newly diagnosed musculoskeletal disorders, self-reported musculoskeletal pain, discomfort or fatigue, and productivity or work performance. We considered workload changes as secondary outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles, abstracts and full texts for study eligibility, extracted data and assessed risk of bias. We contacted authors for additional study data where required. We performed meta-analyses, where possible, and we assessed the overall quality of the evidence for each outcome of each comparison using the five GRADE considerations.

MAIN RESULTS

We included six studies (373 workers), four parallel RCTs, one cross-over RCT, and one combined parallel plus cross-over RCT. At least 295 of the employees were female and at least 39 male; for the remaining 39 employees, the sex was not specified in the study trial. The studies investigated different work-break frequencies (five studies) and different work-break types (two studies). None of the studies investigated different work-break durations. We judged all studies to have a high risk of bias. The quality of the evidence for the primary outcomes of self-reported musculoskeletal pain, discomfort and fatigue was low; the quality of the evidence for the primary outcomes of productivity and work performance was very low. The studies were executed in Europe or Northern America, with none from low- to middle-income countries. One study could not be included in the data analyses, because no detailed results have been reported.Changes in the frequency of work breaksThere is low-quality evidence that additional work breaks may not have a considerable effect on musculoskeletal pain, discomfort or fatigue, when compared with no additional work breaks (standardised mean difference (SMD) -0.08; 95% CI -0.35 to 0.18; three studies; 225 participants). Additional breaks may not have a positive effect on productivity or work performance, when compared with no additional work breaks (SMD -0.07; 95% CI -0.33 to 0.19; three studies; 225 participants; very low-quality evidence).We found low-quality evidence that additional work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 1.80 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 15 participants), when compared to work breaks as needed (i.e. microbreaks taken at own discretion). There is very low-quality evidence that additional work breaks may have a positive effect on productivity or work performance, when compared to work breaks as needed (MD 542.5 number of words typed per 3-hour recording session; 95% CI 177.22 to 907.78; one study; 15 participants).Additional higher frequency work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 11.65 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 10 participants; low-quality evidence), when compared to additional lower frequency work breaks. We found very low-quality evidence that additional higher frequency work breaks may not have a considerable effect on productivity or work performance (MD -83.00 number of words typed per 3-hour recording session; 95% CI -305.27 to 139.27; one study; 10 participants), when compared to additional lower frequency work breaks.Changes in the duration of work breaksNo trials were identified that assessed the effect of different durations of work breaks.Changes in the type of work breakWe found low-quality evidence that active breaks may not have a considerable positive effect on participant-reported musculoskeletal pain, discomfort and fatigue (MD -0.17 on a 1-7 NRS scale; 95% CI -0.71 to 0.37; one study; 153 participants), when compared to passive work breaks.Relaxation work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue, when compared to physical work breaks (MD 0.20 on a 1-7 NRS scale; 95% CI -0.43 to 0.82; one study; 97 participants; low-quality evidence).

AUTHORS' CONCLUSIONS

We found low-quality evidence that different work-break frequencies may have no effect on participant-reported musculoskeletal pain, discomfort and fatigue. For productivity and work performance, evidence was of very low-quality that different work-break frequencies may have a positive effect. For different types of break, there may be no effect on participant-reported musculoskeletal pain, discomfort and fatigue according to low-quality evidence. Further high-quality studies are needed to determine the effectiveness of frequency, duration and type of work-break interventions among workers, if possible, with much higher sample sizes than the studies included in the current review. Furthermore, work-break interventions should be reconsidered, taking into account worker populations other than office workers, and taking into account the possibility of combining work-break intervention with other interventions such as ergonomic training or counselling, which may may possibly have an effect on musculoskeletal outcomes and work performance.

An ergonomic field study to evaluate the effects of a rotatable handle piece on muscular stress and fatigue as well as subjective ratings of usability, wrist posture and precision during laparoscopic surgery: an explorative pilot study

PURPOSE

The interface between surgeon and the laparoscopic instrument is an important factor in biomechanical stress that may increase the risk of musculoskeletal complaints in surgeons. This article investigates the effect of a laparoscopic instrument with a rotatable handle piece (rot-HP) on muscular stress and fatigue during routine laparoscopic procedures (LP) as well as usability, wrist posture and working precision.

METHODS

40 LP (subtotal hysterectomies) performed by 11 surgeons were investigated. 20 LP were carried out with the rot-HP and 20 with a fixed (standard) laparoscopic handle piece instrument. Shoulder and arm muscle activity was monitored via surface electromyography (sEMG). The electrical activity (EA) and median power frequency (MPF) were used to determine muscular stress and fatigue. Usability, wrist posture, and working precision between handle piece conditions were assessed by a survey.

RESULTS

Using the rot-HP did not reduce muscular stress. A tendency of muscular fatigue (increasing EA, decreasing MPF) occurred in the upper trapezius, middle deltoid and extensor digitorum muscles; however, no differences were found between handle pieces. Wrist posture was more comfortable using the rot-HP and working precision and usability tended to be preferred using the standard handle piece.

CONCLUSIONS

Although wrist posture seemed to be optimized by the rot-HP, no effect on muscular stress and fatigue was observed in routine LP (< 60 min duration). Optimization of wrist posture may provide positive effects in mid- or long-term procedures. However, sufficient familiarization with the new instrument is crucial since working precision and usability could be impaired.

Effectiveness and efficiency of different weight machine-based strength training programmes for patients with hip or knee osteoarthritis: a protocol for a quasi-experimental controlled study in the context of health services research

INTRODUCTION

Osteoarthritis is a chronic musculoskeletal disease with a major impact on the individual and the healthcare system. As there is no cure, therapy aims for symptom release and reduction of disease progression. Physical exercises have been defined as a core treatment for osteoarthritis. However, research questions related to dose response, sustainability of effects, economic efficiency and safety are still open and will be evaluated in this trial, investigating a progressive weight machine-based strength training.

METHODS AND ANALYSIS

This is a quasi-experimental controlled trial in the context of health services research. The intervention group (n=300) is recruited from participants of an offer for insurants of a health insurance company suffering from hip or knee osteoarthritis. Potential participants of the control group are selected and written to from the insurance database according to predefined matching criteria. The final statistical twins from the control responders will be determined via propensity score matching (n=300). The training intervention comprises 24 supervised mandatory sessions (2/week) and another 12 facultative sessions (1/week). Exercises include resistance training for the lower extremity and core muscles by use of weight machines and small training devices. The training offer is available at two sites. They differ with respect to the weight machines in use resulting in different dosage parameters. Primary outcomes are self-reported pain and function immediately after the 12-week intervention period. Health-related quality of life, self-efficacy, cost utility and safety will be evaluated as secondary outcomes. Secondary analysis will be undertaken with two strata related to study site. Participants will be followed up 6, 12 and 24 months after baseline.

TRIAL REGISTRATION NUMBER

German Clinical Trial Register DRKS00009257. Pre-results.

Long-Lasting Changes in Muscle Twitch Force During Simulated Work While Standing or Walking

OBJECTIVE

The aim of this study was to evaluate the long-lasting effects of prolonged standing work on a hard floor or floor mat and slow-pace walking on muscle twitch force (MTF) elicited by electrical stimulation.

BACKGROUND

Prolonged standing work may alter lower-leg muscle function, which can be quantified by changes in the MTF amplitude and duration related to muscle fatigue. Ergonomic interventions have been proposed to mitigate fatigue and discomfort; however, their influences remain controversial.

METHOD

Ten men and eight women simulated standing work in 320-min experiments with three conditions: standing on a hard floor or an antifatigue mat and walking on a treadmill, each including three seated rest breaks. MTF in the gastrocnemius-soleus muscles was evaluated through changes in signal amplitude and duration.

RESULTS

The significant decrease of MTF amplitude and an increase of duration after standing work on a hard floor and on a mat persisted beyond 1 hr postwork. During walking, significant MTF metrics changes appeared 30 min postwork. MTF amplitude decrease was not significant after the first 110 min in any of the conditions; however, MTF duration was significantly higher than baseline in the standing conditions.

CONCLUSION

Similar long-lasting weakening of MTF was induced by standing on a hard floor and on an antifatigue mat. However, walking partially attenuated this phenomenon.

APPLICATION

Mostly static standing is likely to contribute to alterations of MTF in lower-leg muscles and potentially to musculoskeletal disorders regardless of the flooring characteristics. Occupational activities including slow-pace walking may reduce such deterioration in muscle function.

Effectiveness and efficiency of an 11-week exercise intervention for patients with hip or knee osteoarthritis: a protocol for a controlled study in the context of health services research

Background

Osteoarthritis is the most common reason for pain in older adults, and the individual and economic burden of this disease is immense. The chronic character of osteoarthritis requires a long-term therapeutic treatment. In this regard life-style interventions such as physical exercises that can be carried out by the patient himself are recommended as first line treatment. There is evidence for the short-term benefit of exercise therapy in terms of pain reduction and physical functioning. Nonetheless research agendas highlight the need for multifaceted interventions that incorporate exercise strategies into patient care. Studies should be conducted with appropriate sample sizes and should allow statements on long-term effects as well as cost-utility and safety. These open questions are under the scope of this study.

Methods/design

This is a controlled study in the context of health services research. The study population consists of n = 1400 subjects with hip or knee osteoarthritis. The intervention group will be recruited from participants of a country-wide health insurance offer for people with hip or knee osteoarthritis. Potential participants for the control group (ratio 10:1 (control vs. intervention) will be filtered out from the insurance data base according to pre-defined matching criteria and asked by letter for their participation. The final statistical twins from the responders (1:1) will be determined via propensity score matching. The progressive training intervention comprises 8 supervised group sessions, supplemented by home exercises (2/week over 11 weeks). Exercises include mobilization, strengthening and training of postural control. Primary outcomes are pain and function measured with the WOMAC Index immediately after the intervention period. Among other things, health related quality of life, self-efficacy, cost utility and safety will be evaluated as secondary outcomes. Participants will be followed up 6, 12 and 24 month after baseline.

Discussion

Results of this trial will document the effects of clinical as well as economic outcomes in a regular health care setting on the basis of a large sample size. As such, results of this trial might have great impact on future implementations of group- and home-based exercises in hip or knee osteoarthritis.

Trail registration

German Clinical Trial Register DRKS00009251. Registered 10 September 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3030-0) contains supplementary material, which is available to authorized users.

Exercise therapy in hip osteoarthritis--a randomized controlled trial

BACKGROUND

Roughly one in ten persons in the industrialized world suffers from hip osteoarthritis, a disease for which there is no cure. The goal of conservative therapy is to relieve symptoms, preferably with methods that let patients assume responsibility for their own treatment, e.g., physical training.

METHOD

In a randomized controlled trial, we studied the effectiveness of twelve weeks of exercise therapy in patients with hip osteoarthritis (THüKo), compared to no treatment (control group) and placebo ultrasound treatment of the hip (placebo ultrasound group). The primary endpoint was a comparison of the pain scores of the intervention versus control groups on the generic SF-36 health questionnaire. Secondary endpoints included comparisons across all three study groups of scores on the 7 other scales of the SF-36 and on the pain, physical function, and stiffness scales of the osteoarthritis-specific WOMAC Index. The statistical analysis was performed with ANCOVA, with baseline values as a covariate. Between-group effects were subsequently tested pairwise (two-tailed t-tests, alpha = 0.05).

RESULTS

As for the primary endpoint, pain reduction was significantly greater in the intervention than in the control group (mean difference 5.7 points, 95% confidence interval [CI] 0.4-11.1 points, p = 0.034). The comparisons across all three study groups (i.e., secondary endpoints, with 71 subjects in the intervention group, 68 in the control group, and 70 in the placebo group) revealed no significant between-group effects with respect to the SF-36. On the WOMAC Index, however, statistically significant differences were found for pain reduction between the intervention and control group (mean difference 7.4 points, 95% CI 3.0-11.8, p = 0.001) and between the intervention and placebo group (mean difference 5.1 points, 95% CI 0.7-9.4, p = 0.024). Comparable mean differences were also found for functional improvement.

CONCLUSION

Twelve weeks of exercise therapy in hip osteoarthritis patients of normal vitality reduced pain and improved physical function. No significant improvement was found in these patients' general health-related quality of life.

Effect of a laparoscopic instrument with rotatable handle piece on biomechanical stress during laparoscopic procedures

OBJECTIVE

To investigate the effect of a pistol grip laparoscopic instrument with a rotatable handle piece (rot-HP) on biomechanical stress and precision as well as a possible interaction between the instrument and working height (WH).

BACKGROUND

Biomechanical stress induced by laparoscopic surgery (LS) is associated with work-related upper limb musculoskeletal disorders in surgeons. Ergonomic handle designs of laparoscopic instruments may reduce the risk of musculoskeletal disorders.

METHODS

Without LS experience, 57 healthy subjects (30 women; 27 men, median age: 26) were observed while performing a laparoscopic exercise. Subjects had to pick up coloured pins and place them into a colour-coded wooden set-up inside a pelvitrainer. The exercise was performed at two WHs using the rot-HP and a standard laparoscopic (fixed) handle piece in randomized sequence. Biomechanical stress was monitored via surface electromyography (sEMG) on fife muscles from the upper limb and shoulder region. Further, the wrist angle (palmar and dorsi flexion) and posture of the dominant upper arm were recorded. Precision was assessed using the number of validly placed pins and process time.

RESULTS

sEMG parameters and upper arm postures indicated no differences in biomechanical stress related to either laparoscopic handle piece. The higher WH was associated with higher trapezius and deltoid activity and elevated arm postures (p < 0.05). Neutral wrist positions were more frequent using the rot-HP, and the lower WH resulted in slightly more neutral wrist positions. Precision was similar during all experimental conditions.

CONCLUSIONS

The rot-HP did not decrease biomechanical stress in the shoulder or lower arm muscles. However, wrist angle position may be optimized without affecting precision. Long-term effects of the rot-HP on preventing complaints of the upper extremity should be evaluated. Low WH is recommended to reduce biomechanical stress in the shoulder during laparoscopic surgery.

Stiffness, pain, and hip muscle strength are factors associated with self-reported physical disability in hip osteoarthritis

BACKGROUND

Physical disability (PD) is common among patients with osteoarthritis (OA) of the hip. Exercise therapy is proposed to be a potential intervention to reduce PD. However, the optimal targets of an exercise program are not known.

PURPOSE

The aim of the present study was to identify factors that explain the level of self-reported PD in patients with hip OA. Knowledge of these factors will help develop specific and effective exercise programs.

METHODS

Data from 149 patients with hip OA (85 men and 64 women) were analyzed. Self-reported PD was quantified using the physical function subscale of the Western Ontario and McMaster index. A stepwise regression analysis was conducted to identify significant factors associated with self-reported PD.

RESULTS

Stiffness, pain, and hip muscle strength were found to be significant factors related to the level of self-reported PD in hip OA. These factors explained 59% (r adjusted = 0.59) of the variance. Body mass index, gender, age, and passive internal hip rotation and flexion range of motion explained only minor parts of the dependent variable self-reported PD.

DISCUSSION AND CONCLUSION

Stiffness, pain, and hip muscle strength are associated with self-reported PD in hip OA. It is imperative that exercise treatments for hip OA include strategies to modify these factors. Further research should evaluate their role in preventing hip OA.

Development of an arm support system to improve ergonomics in laparoscopic surgery: study design and provisional results

Background

Laparoscopic surgery (LS) induces physical stress to the surgeon that is associated with an increased prevalence of musculoskeletal pain and injury in the shoulder–neck region. The aim of this research project is to develop an arm support system (ASsyst) that reduces physical stress and is applicable to various laparoscopic interventions and operation room settings.

Methods

A systematic approach to develop an ASsyst started in October 2012 consisting of five consecutive steps. In step 1, 14 laparoscopic interventions were observed using subjective and objective measures to determine key indicators for the conception of an ASsyst in LS. In step 2, an expert workshop was held to find and evaluate solutions to generate concepts for a support system based on the results of step 1 and general methods. During the third step, prototypes of ASsyst were tested in an experimental setting. Steps 4 and 5 are currently in process and include the final development of the ASsyst using the most promising concept for the evaluation during simulated LS.

Results

Increased levels of physical stress were found in LS. Asymmetric strains were common. Three prototypes of ASsyst emerged from step 1 and 2. These prototypes were a cable construction with a noose for the lower arm, a support from below the elbow and a pneumatic vest supporting the upper arm. The experimental testing of these prototypes demonstrated reduced physical stress when compared to the unsupported environment. The support from below the elbow seemed to be the most practical in terms of implementation in various operation room settings and acceptance by surgeons. Step 4 and 5 are still in process.

Conclusions

Ergonomic problems have been identified in LS that could be addressed by an ASsyst. The concept of supporting the elbow from below has been found to be the most promising approach.

Efficacy of conservative treatment regimes for hip osteoarthritis--evaluation of the therapeutic exercise regime "Hip School": a protocol for a randomised, controlled trial

BACKGROUND

Hip osteoarthritis (hip OA) is a disease with a major impact on both national economy and the patients themselves. Patients suffer from pain and functional impairment in activities of daily life which are associated with a decrease in quality of life. Conservative therapeutic interventions such as physical exercises aim at reducing pain and increasing function and health-related quality of life. However, there is only silver level evidence for efficacy of land-based physical exercise in the treatment of hip OA. The purpose of this randomized controlled trial is to determine whether the specific 12-week exercise regime "Hip School" can decrease bodily pain and improve physical function and life quality in subjects with hip osteoarthritis.

METHODS/DESIGN

217 participants with hip OA, confirmed using the clinical score of the American College of Rheumatology, are recruited from the community and randomly allocated to one of the following groups: (1) exercise regime "Hip School", n = 70; (2) Non-intervention control group, n = 70; (3) "Sham" ultrasound group, n = 70; (4) Ultrasound group, n = 7. The exercise regime combines group exercises (1/week, 60-90') and home-based exercises (2/week, 30-40'). Sham ultrasound and ultrasound are given once a week, 15'. Measures are taken directly prior to (M1) and after (M2) the 12-week intervention period. Two follow-ups are conducted by phone 16 and 40 weeks after the intervention period. The primary outcome measure is the change in the subscale bodily pain of the SF36 from M1 to M2. Secondary outcomes comprise the WOMAC score, SF36, isometric strength of hip muscles, spatial-temporal and discrete measures derived from clinical gait analysis, and the length of the centre of force path in different standing tasks. An intension-to-treat analysis will be performed using multivariate statistics (group × time).

DISCUSSION

Results from this trial will contribute to the evidence regarding the effect of a hip-specific exercise regime on physical function, pain, and health-related quality of life in patients with hip osteoarthritis.

TRIAL REGISTRATION

German Clinical Trial Register DRKS00000651.

Feasibility and efficacy of an 8-week progressive home-based strengthening exercise program in patients with osteoarthritis of the hip and/or total hip joint replacement: a preliminary trial

The feasibility and efficacy of an additional progressive home-based strengthening exercise program (PHSEP) on subjects that already attended supervised institutional exercise therapy was investigated. Thirty-six hip patients with hip osteoarthritis (OA) and/or total hip replacement in at least one hip joint were randomly assigned to an intervention group (IG) or a control group (CG). IG (18 patients, mean age 64.9, standard deviation (SD) 7.5) followed an 8-week PHSEP in addition to their weekly institutional exercise therapy, while CG (18 patients, mean age 64.7, SD 9) solely continued the weekly institutional exercise sessions. Before and after the intervention period, strength of hip muscles was quantified applying isokinetic concentric and isometric measurements, and health-related quality of life was monitored using the SF36 questionnaire. Adherence to the exercise program was evaluated using exercise logs. The PHSEP was feasible for all subjects in IG with an adherence of 99%. Exercise logs reported that pain resulting from the PHSEP was low. Increased strength in isokinetic concentric hip adduction (13%) and isometric hip abduction (9%), adduction (12%), and flexion (7%) was found in IG in comparison to CG. The results of the SF36 did not change during the intervention period. Consequently, supervised institutional exercise therapy supplemented by a PHSEP could increase hip muscle strength in patients with hip OA and/or total hip replacement. However, further research should evaluate the optimal frequency and duration of such supplementary sessions and their potential to increase physical function and reduce pain.

Tricuspid valve endocarditis due to a jet lesion detected by echocardiography in a 27-year old man with congenital ventricular septal defect

The case of an non-addict young caucasian with isolated tricuspid valve endocarditis in congenital ventricular septal defect (VSD) is presented. Despite antibiotic treatment the patient suffered from recurrent right sided pneumonias. A computed tomography of the chest revealed an abscess localized in the right lower lung with signs of cavitation. Echocardiography identified a vegetation located at the anterior tricuspid leaflet due to a jet lesion through the VSD. ECG-gated MRI revealed normal left ventricular function and localized the septal defect and a jet against the anterior tricuspid valve leaflet. The patient underwent open heart surgery and the VSD was closed. Now, two years later, the patient is free from any symptoms or complications. This case illustrates that noninvasive techniques like echocardiography and ECG-gated MRI can not only accurately image cardiac anatomy in patients with ventricular septal defect but additionally provide information about the pathomechanism of the development of jet lesions resulting in valvular vegetations. Operative correction of underlying cardiac disease in nonaddicts with complicating tricuspid valve endocarditis might be a favourable treatment especially when antibiotic treatment fails to cure the infection.